Insect pests cost the general public billions of dollars annually in losses. These losses include the expense of controlling insect pests as well as crop loss and property damage caused by the pests. Economically significant insect pests in United States include Solenopsis spp. For Solenopsis invicta specifically, the well-documented fire ant currently infests over 320 million acres in the United States and over $6 billion per year is spent for control, agricultural losses, medical costs, and damage repair (as reported in Lard, C. F., et al., 2006, “An economic impact of imported fire ants in the United States of America.” Texas A&M University, College Station, Tex. Available online at fireantecon.tamu.edu). Control of Solenopsis invicta is generally achieved through traditional chemical pesticides and/or delayed acting pesticides delivered as baits.
Chemical pesticides are the primary tools used to combat insect pests. However, use of traditional chemical pesticides has disadvantages, including non-target effects on neutral or beneficial insects, as well as other animals. Chemical pesticide usage also can lead to chemical residue run-off into streams and seepage into water supplies resulting in ecosystem/environment damage. In addition, animals higher in the food chain are at risk when they consume pesticide contaminated crops or insects. The handling and application of chemical pesticides also presents exposure danger to the public and professionals, and could lead to accidental dispersal into unintended environmentally sensitive areas. In addition, prolonged chemical pesticide application may result in an insect population becoming resistance to a chemical pesticide. In order to control a traditionally chemical resistant-pest, new more potent chemical pesticides must be utilized, which in turn will lead to another resistance cycle. As such, there is a need in the art to control pest populations without the disadvantages of traditional chemical pesticides.
Genes associated with signal transduction of neurohormones represent potential pesticide targets. One neurohormone gene family is the pheromone-biosynthesis-activating neuropeptide receptor (PBAN-R) gene family. PBAN-R is expressed in target tissue(s) in developmental and adult stages. The PBAN-R activates a specific physiological function after binding to a pheromone biosynthesis activating neuropeptide/pyrokinin (PBAN/pyrokinin) peptide ligand. To date, over 250 PBAN/pyrokinin family peptide ligands have been identified. Research on the function(s) of these peptide ligand(s)/receptor(s) has largely focused on the regulation of sex pheromones (Raina et al., 1989), and a variety of other physiological functions depending on life stages and insect groups: examples of known functions are induction of cuticle melanization, regulation of egg or pupal diapause, control of hind gut muscle (Matsumoto et al., 1990; Suwan et al., 1994; Sun et al., 2003; Nachman et al., 1986). These multi-functional PBAN/pyrokinin peptides are good targets to screen specific antagonist(s) through specific receptor-based expression. All PBAN-Rs belong to a family of G-protein coupled-receptors (GPCRs) which are 7-transmembrane receptors containing an extracellular N-terminal and intracellular C-terminal end in the cell membrane. SEQ ID NO: 13 GSGEDLSYGDAYEVDEDDHPLFVPRL is the specific PBAN ligand amino acid sequence for Solenopsis invicta. 
The PBAN/Pyrokinin gene is expressed in all fire ant developmental stages (J. of Insect Physiology, 2012, 58, 1159-1165), as well as the adults, suggesting functions for the peptide ligands and their associated GPCRs throughout the fire ant life cycle. In addition, prevention of PBAN-R gene expression led to negative phenotypic effects on immature and adult fire ants (See, e.g., U.S. Pat. No. 8,575,328). Given the importance of PBAN-R in essential developmental and adult fire ant stages, discovery of novel peptide ligands that strongly bind to PBAN-R could prevent normal functioning of PBAN-R and act as alternatives or additives to classical chemical pesticides. To that end, there is a need to develop methodology to make and discover peptide ligands of PBAN-R that are effective for insect-control.